1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154

// Copyright 2020 Contributors to the Parsec project.
// SPDX-License-Identifier: Apache-2.0
//! # PsaAsymmetricEncrypt operation
//!
//! Encrypt a short message with a public key.

use super::psa_key_attributes::Attributes;
use crate::operations::psa_algorithm::AsymmetricEncryption;
use crate::requests::ResponseStatus;
use derivative::Derivative;

/// Native object for asymmetric encryption operations.
#[derive(Derivative)]
#[derivative(Debug)]
pub struct Operation {
    /// Defines which key should be used for the encryption operation.
    pub key_name: String,
    /// An asymmetric encryption algorithm that is compatible with the key type
    pub alg: AsymmetricEncryption,
    /// The short message to be encrypted.
    #[derivative(Debug = "ignore")]
    pub plaintext: zeroize::Zeroizing<Vec<u8>>,
    /// Salt to use during encryption, if supported by the algorithm.
    #[derivative(Debug = "ignore")]
    pub salt: Option<zeroize::Zeroizing<Vec<u8>>>,
}

impl Operation {
    /// Validate the contents of the operation against the attributes of the key it targets
    ///
    /// This method checks that:
    /// * the key policy allows encrypting messages
    /// * the key policy allows the encryption algorithm requested in the operation
    /// * the key type is compatible with the requested algorithm
    /// * if the algorithm is RsaPkcs1v15Crypt, it has no salt (it is not compatible with salt)
    /// * the message to encrypt is valid (not length 0)
    pub fn validate(&self, key_attributes: Attributes) -> crate::requests::Result<()> {
        key_attributes.can_encrypt_message()?;
        key_attributes.permits_alg(self.alg.into())?;
        key_attributes.compatible_with_alg(self.alg.into())?;
        if (self.alg == AsymmetricEncryption::RsaPkcs1v15Crypt && self.salt.is_some())
            || self.plaintext.is_empty()
        {
            return Err(ResponseStatus::PsaErrorInvalidArgument);
        }
        Ok(())
    }
}

/// Native object for asymmetric encrypt result.
#[derive(Derivative)]
#[derivative(Debug)]
pub struct Result {
    /// The `ciphertext` field contains the encrypted short message.
    #[derivative(Debug = "ignore")]
    pub ciphertext: zeroize::Zeroizing<Vec<u8>>,
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::operations::psa_algorithm::{AsymmetricEncryption, Hash};
    use crate::operations::psa_key_attributes::{Lifetime, Policy, Type, UsageFlags};

    fn get_attrs() -> Attributes {
        let mut usage_flags = UsageFlags::default();
        let _ = usage_flags.set_encrypt();
        Attributes {
            lifetime: Lifetime::Persistent,
            key_type: Type::RsaKeyPair,
            bits: 256,
            policy: Policy {
                usage_flags,
                permitted_algorithms: AsymmetricEncryption::RsaPkcs1v15Crypt.into(),
            },
        }
    }

    #[test]
    fn validate_success() {
        (Operation {
            key_name: String::from("some key"),
            alg: AsymmetricEncryption::RsaPkcs1v15Crypt,
            plaintext: vec![0xff, 32].into(),
            salt: None,
        })
        .validate(get_attrs())
        .unwrap();
    }

    #[test]
    fn cannot_encrypt() {
        let mut attrs = get_attrs();
        attrs.policy.usage_flags = UsageFlags::default();
        assert_eq!(
            (Operation {
                key_name: String::from("some key"),
                alg: AsymmetricEncryption::RsaPkcs1v15Crypt,
                plaintext: vec![0xff, 32].into(),
                salt: None,
            })
            .validate(attrs)
            .unwrap_err(),
            ResponseStatus::PsaErrorNotPermitted
        );
    }

    #[test]
    fn wrong_algorithm() {
        assert_eq!(
            (Operation {
                key_name: String::from("some key"),
                alg: AsymmetricEncryption::RsaOaep {
                    hash_alg: Hash::Sha256,
                },
                plaintext: vec![0xff, 32].into(),
                salt: None,
            })
            .validate(get_attrs())
            .unwrap_err(),
            ResponseStatus::PsaErrorNotPermitted
        );
    }

    #[test]
    fn invalid_plaintext() {
        assert_eq!(
            (Operation {
                key_name: String::from("some key"),
                alg: AsymmetricEncryption::RsaPkcs1v15Crypt,
                plaintext: vec![].into(),
                salt: None,
            })
            .validate(get_attrs())
            .unwrap_err(),
            ResponseStatus::PsaErrorInvalidArgument
        );
    }

    #[test]
    fn salt_with_rsapkcs1v15crypt() {
        assert_eq!(
            (Operation {
                key_name: String::from("some key"),
                alg: AsymmetricEncryption::RsaPkcs1v15Crypt,
                plaintext: vec![0xff, 32].into(),
                salt: Some(zeroize::Zeroizing::new(vec![0xff, 32])),
            })
            .validate(get_attrs())
            .unwrap_err(),
            ResponseStatus::PsaErrorInvalidArgument
        );
    }
}